Relay



' 1 1,641,285 S 1927' D. D. MILLER RELAY Filed Sept. 6 1924 Fig] CURRENTlnvenfor; Daniel 0. M/7/e/r by M W Patented Sept. 6, 1927.

- S TE DANIEL D. MILLER, on NEW YORK, NYIYQ assrcuon TO wns'rnnnELECTRIC COMPANY,

- INCQRPORATED, on NEW YORK, N. Y., GOREORATION or NEW YORK.

1,641,285 PATENT @OFFICE. a

' RELAY.

Application filed September 6, 1924. Seria1 No. 736,382.

phone circuits, its, object being to produce a reliable marginal relay.

In accordance with this invention the relay is designed with acomparatively heavy armature and a graduated contact spring arrangementwhereby the spring pressure is built up, gradually beforeithe finalcontact is made. Through an. armature of this nature arelay is producedwhich depends for its marginal operation on a'difi'erence in time ratherthan a difference incurrent as has been the case heretofore. v

The drawings show two diagrammatic illustrations embodying features ofthis invention and a graph illustrating the principle whereby thedifference in time is gained.

In 1 a relay is shown connectedin a circuit having two alternatearrangements whereby a difference in the operation may be explained;

Fig. 2 shows two curves manner in which current buildsup in circuitshaving differentcharacteristics; and

Fig. 3 is a diagrammatic illustration of a relay winding in a circuitequivalent to that shown in Fig. 1, but arranged somewhat differently.

It is well known that when an electric circuit is closed there is aperiod during which the current rises from Zero value to its ultimatevalue. The manner in which the current rises has heretofore beeninvestigated and is now well known, the formula shown on the drawingbeing a well-known exponential formula by means of which such curves maybe calculated. The curve designated 1 illustrates the rise of current ina circuit in which there is a large amount of inductance, and. the curvedesignated 2 illustrates the rise. of current in a circuit in whichthere .is a comparatively small amount of inductance.

Referring now to Fig. 1 it will be noted that by means of a switch 3 therelay winding 1 may beincluded in a circuit with battery 5 eitherthrough a resistance 6 or an inductance 7. If the switch 3 is moveddownward so as to include the resistance 6 in series with a relaywinding, then the cur-- rent will rise according to curve 2,.and if theswitch 3 is moved upward so as to include the inductance 7 1n serieswith the re laywindin then the current will'rise no illustrating thecording to curve 1. In this connection it is assumed that the ohmicresistance of 7 is the came as the ohmic resistance of 6, so that theultimate current through the winding of reflay 1 will be the same ineither case.

The relay illustrated in Fig. 1 consists of the winding 4, the core 8and the armature 9. The force with which the armature 9 is drawn towardthe core 8 depends both on the current flowing through the circuit ofthe winding 4 and the number of turns. This force; is also controlled bythe air gap betweenthe core and the armature so that with a certaincurrent flowing throughthe winding ofthe relay, the force tending toattract the armature will be greaterwh'en the air gap is small thanwhenit islarge. As the armaturejmoves downward, a spring 10 isencountered and the tension developed by this spring must be overcomebefore the armature can continue its downward move ment. When thistension has'been overcome then another spring 11 is encountered and thetension developed by this spring must .also be overcome. If the circuitis closed through the inductance 7,then due to the fact that the currentrises slowly, the armature will not be immediately attracted and when itfinally moves down and encounters the resistance of spring 10, it willbe slowed 'up until the current has risen suflicien'tly to produce theadditional amount of force needed to overcome the tension of thisspring. The relay is so adjusted that under this condition the combinedspring tension of spring 10. and spring 11 is such that springll cannotbe moved far enough downward to make contact with the spring 12.

If, howeventhe circuit is closed through the resistancefi, then thecurrent building up faster will cause the armature to move quicker andsince the armature has a certain amount of weight and is now given acertain amount of speed, there is developed kinetic energy which addedto the-force developed by the relay winding is enough to overcome thetension of springs 10 and 11 and close the closed. Hence it is seen thatif two circuits both of the same ohmic resistance are alternat-elyclosed, and one of these circuits has less inductance than the other,then in the one case the relay will be operated to close an electriccircuit such as one through a signal lamp 13, and in the other case therelay will not be operated.

This same action may be illustrated in Fig. 3 wherein the switch 14 whenthrown to its lower position closes a circuit directly to battery 15 andin the other case through a resistance 16 to a battery 17. The battery17 is of higher potential than the battery 15, but the inclusion of theresistance 16 in the one case limits the current so that the finalcurrent flow in each case is the same. The Winding 18 necessarily has acertain amount of inductance and hence when the switch 15 is closed soas to form a circuit through the battery 15, the relation between theresistance and inductance in the circuit is different than when theswitch 14 is thrown so as to include resistance 16 in series with thehigher potential battery 17 In this case and for the reasons givenhereinbefore the relay ,18 will act to close a secondary circuit whenthe switch 14 is moved to include the resistance 16 in series with itand will not operate when a circuit is closed through the battery 15.

What is claimed is:

Means for producing a marginal relay operation comprising a relayprovided with an armature having an appreciable mass, a source ofcurrent and a circuit including said source of current and said relay,said circuit having two branches with means to close each 01 saidbranches separately, each said branch having means to render the steadyflow of current the same, and other means to render the transientcurrents at corresponding times during the building up of current insaid branches different whereby a greater amount of energy is stored insaid armature during the first part of its stroke when said relay isenergized through one said branch than when said relay is energizedthrough the other said branch, and spring means for adjusting said relayso that it will operate in one said branch and will not operate in theother said branch.

In witness whereof, I hereunto subscribe my name this 3 day of SeptemberA. 1).,

1924. DANIEL D. MILLER.

